Abstract
Dietary choline can impact systemic immunity, but it remains unclear whether this is primarily via direct impacts on immune cells or secondary effects of altered metabolic function. To determine whether increased choline concentrations (3.2, 8.2, 13.2 μM) in cell culture alter the function of bovine innate and adaptive immune cells, we isolated cells from dairy cows in early and mid-lactation as models of immuno-compromised and competent cells, respectively. Phagocytic and killing capacity of isolated neutrophils were linearly diminished with increasing doses of choline. In contrast, lymphocyte proliferation was linearly enhanced with increasing doses of choline. Furthermore, increasing doses of choline increased the mRNA abundance of genes involved in the synthesis of choline products (betaine, phosphatidylcholine, and acetylcholine) as well as muscarinic and nicotinic acetylcholine receptors in a quadratic and linear fashion for neutrophils and monocytes, respectively. Phagocytic and killing capacity of neutrophils and proliferation of lymphocytes were not affected by stage of lactation or its interaction with choline or LPS. In neutrophils from early lactation cows, choline linearly increased the mRNA abundance of muscarinic and nicotinic cholinergic receptors, whereas choline-supplemented monocytes from mid-lactation cows linearly increased the mRNA abundance of several genes coding for choline metabolism enzymes. These data demonstrate that choline regulates the inflammatory response of immune cells and suggest that the mechanism may involve one or more of its metabolic products.
Highlights
Choline is a quaternary amine obtained from the diet which can be synthesized by several organs, primarily the liver [1]
The current study used isolated immune cells to assess impacts of choline on functional and transcriptional responses in vitro to avoid the potential confounding effects of metabolic shifts induced by choline
We found evidence of antiinflammatory responses to additional choline in innate immune cells, whereas the proliferation rate of lymphocytes was increased by increasing doses of choline
Summary
Choline is a quaternary amine obtained from the diet which can be synthesized by several organs, primarily the liver [1]. Betaine, is primarily synthesized in the liver and kidney and serves as a methyl donor, aiding in the regeneration of methionine and S-adenosylmethionine [2]. The neurotransmitter acetylcholine is primarily synthesized in cholinergic neurons, where. Choline Regulates Bovine Immune Cells activated muscarinic and nicotinic receptors trigger second messengers [4], but it has been detected in bovine blood at ∼40× greater concentrations than in human blood [5]. Some studies have identified muscarinic and nicotinic cholinergic receptors in innate and adaptive immune cells from rodents and humans [6,7,8]
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